Hi satch428,
If you need to have the 1st sheet start a 13 and then automatically number the sheets after that, then you'll want to create 12 empty sheets and set them not to be printed (right-click on the sheet node and choose Edit Sheet > Exclude From Printing).
If you are creating a drawing file for sheet 13, and another drawing file for sheet 14, etc. Then you'll want to edit the title block definition and set the sheet number to be a prompted entry that you can enter manually.
I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com